Problem: Which of the following numbers is a multiple of 5? ${57,70,73,86,106}$
Explanation: The multiples of $5$ are $5$ $10$ $15$ $20$ ..... In general, any number that leaves no remainder when divided by $5$ is considered a multiple of $5$ We can start by dividing each of our answer choices by $5$ $57 \div 5 = 11\text{ R }2$ $70 \div 5 = 14$ $73 \div 5 = 14\text{ R }3$ $86 \div 5 = 17\text{ R }1$ $106 \div 5 = 21\text{ R }1$ The only answer choice that leaves no remainder after the division is $70$ $ 14$ $5$ $70$ We can check our answer by looking at the prime factorization of both numbers. Notice that the prime factors of $5$ are contained within the prime factors of $70$ $70 = 2\times5\times7 5 = 5$ Therefore the only multiple of $5$ out of our choices is $70$. We can say that $70$ is divisible by $5$.